The effect of Cr alloying on defect migration at Ni grain boundaries

Abstract

Mass transport along grain boundaries in alloys depends not only on the atomic structure of the boundary, but also its chemical make-up. In this work, we use molecular dynamics to examine the effect of Cr alloying on interstitial and vacancy-mediated transport at a variety of grain boundaries in Ni. We find that, in general, Cr tends to reduce the rate of mass transport, an effect which is greatest for interstitials at pure tilt boundaries. However, there are special scenarios in which it can greatly enhance atomic mobility. Cr tends to migrate faster than Ni, though again this depends on the structure of the grain boundary. Further, grain boundary mobility, which is sometimes pronounced for pure Ni grain boundaries, is eliminated on the time scales of our simulations when Cr is present. We conclude that the enhanced transport and grain boundary mobility often seen in this system in experimental studies is the result of non-equilibrium effects and is not intrinsic to the alloyed grain boundary. These results provide new insight into the role of grain boundary alloying on transport that can help in the interpretation of experimental results and the development of predictive models of materials evolution.

Interstitial hydrogen enhances the mobility of some grain boundaries in tungsten

“…MD simulations in the Al-Mg alloy system [34], using a synthetic driving force, showed that the pinning effect of the solute atoms was higher when they had segregated on the GB dislocations compared to when they were distributed in a confined region away from the GB. Recent MD simulations in the Ni-Cr alloy system also predict that Cr reduces the mobility of GBs in Ni [35].…”

Recent advances in computational materials design: methods, applications, algorithms, and informatics

“…This Special Issue highlights topical articles presenting recent advances in atomistic modeling methods that use molecular dynamics simulations. The article by Uberuaga et al [7] investigates the complex interplay between the alloying elements and the diffusion behavior of atoms and defects at grain boundaries in Ni. The article by Sose et al [8] investigates the structure and dynamics of confined water in hybrid layered materials.…”

Editorial: The August 2022 cover paper

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This special issue builds on the growing impact of computer modelling in Materials Science with other papers on a wide range of topics including dislocations [2] and grain boundaries [3].Effective July 1, Avinash Dongare has stepped down as a regular Editor of the journal and has been succeeded by Ghanshyam Pilania.

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“…This special issue builds on the growing impact of computer modelling in Materials Science with other papers on a wide range of topics including dislocations [2] and grain boundaries [3].…”